The　semiconductors　have　created　a　great　avenue　in　visible-light　photocatalysis　and　recently　insulator　photocatalysis　has　become　an　appealing　research　spot.　Herein,　a　novel　waste　eggshells　derived　AgBr-CaCO3　heterostructure　was　finely　designed　and　constructed　through　a　simple　co-precipitation　method　for　efficient　antibiotics　photo-degradation　under　visible　light.　The　optimal　heterostructure　achieved　a　pseudo-first-order　kinetic　constant　of　6.0　×　10-2　min−1　for　tetracycline　(TC)　degradation,　with　72　and　seven-fold　enhancement　than　eggshell　(ES)　and　AgBr,　which　also　exhibited　superior　performance　towards　ofloxacin　and　sulfamethoxazole.　The　density　functional　theory　(DFT)　calculations　revealed　that　the　covalent　interaction　of　Ag-O　provided　a　specific　channel　for　interfacial　electrons　transfer　from　the　semiconductor　to　the　insulator　and　thus　greatly　elevated　the　photocatalytic　activity.　The　highly　selective　·CO3–　radicals　generated　by　ES,　as　the　main　active　species,　also　accelerated　the　antibiotics　degradation.　Furthermore,　the　possible　degradation　pathways,　aquatic　toxicity　and　mutagenicity　variation　of　TC　were　thoroughly　elucidated.　This　current　study　illuminated　a　new　pathway　for　the　design　of　insulator　photocatalysts　based　upon　waste　solids　and　demonstrated　its　application　prospect　in　the　field　of　antibiotics　degradation.　©　2023　Elsevier　B.V.